Safety valve for well casings



Aug.16,1932. GRA ETAL 1,872,139

SAFETY VALVE FOR WELL CASINGS Filed July 2, 71928 7m QWMWQ MM atbomwq Patented Aug. 16, 1932 UNITED STATES PATENT OFFICE ELLSWORTH GRAY AND ROBERT A. MUELLER, OF HOUSTON, TEXAS, ASSIGNORS TO GRAY TOOL COMPANY, OF HOUSTON, TEXAS, A CORPORATION OF TEXAS SAFETY VALVE FOR WELL CASINGS Application filed July 2, 1928. Serial No. 289,971.

Our invention relates to a safety valve for use at the upper end of the drill stem in well drilling to be employed when back pressures are encountered due to the downward movement of the drill stem in spudding; or in floating the pipe into the hole, or to gas pressure in the formation tending to blow the fluid from the well.

When av formation is encountered having gas therein it is customary to employ some means to prevent the gas from blowing out of the well. It has been found that if the gas flow starts, moving the column of liquid above it and forcing it from the well, it may break loose with great force and blow the tools from the well and perhaps destroy the rig. Different expedients are employed to prevent this. Blow-out preventers are used to close the space between the casing and drill stem and pump pressure through the drill stem is relied upon to prevent the fluid from blowing out through the drill stem.

It is an object of our invention to provide a valve within the drill stem which will be instantly closed when the gas tends to blow from the well so that the pressure will be prevented from accumulating in the stem, and thus avoiding damage to well equipment.

It is also an object to provide means in connection with the valve whereby it may be opened when desired to allow a vent for the pressure in the well due to dropping of the drill stem in spudding and directing it into channels where it will do no harm.

The invention lies largely in the construction of the parts making up our safety device and the details thereof will be understood from the specifications which follow:

Referring to the drawing herewith:

Fig. 1 is a side view partly in elevation and partly in central vertical section illustrating the attachment employed with our valve.

Fig. 2 is a similar side view partly in section and partly in elevation showing the construction of the valve member.

Fig. 3 is a side elevation illustrating the manner in which the structure is assembled when the valve is open. Fig. 4 is an eniarged view of the valve seat shown in Fig.

- oint.

2; and Fig. 5 is a top plan view of the valve itself. V

In carrying out our invention, we contemplate providing a safety valve which may be coupled into the drill stem at the upper end thereof and between the upper section of the drill stem and the drive stem or kelly The structure of this valve member is shown in F ig. 2. \Ve provide a tubular coupling member 1, the lower end of which is threaded at 2 foratt-achment within the upper tool joint on the drill stem. The up per end of the coupling member 1 is threaded at 3 for engagement with section 4 similar to the box member upon a tool joint having its upper member threaded at5 for engagement with the lower end of the kelly.

The lower coupling member 1 has a chamher 6 at its upper end below the socket 3 in which a valve 7 is adapted to fit. The lower end of the chamber 6 is tapered at -8 leading to a more restricted passage 9 extending downwardly for connection with the drill stem.

The valve member 7 is cup shaped with its opened end extending downwardly. It has a chamber 10 on its interior, the lower part of which is flared outwardly at 11. It is to be noted that the inner diameter of the cup 10 of the valve is greater than the diameter of the passage 9 leading to the valve chamber, so that fluid passing upwardly through the passage 9 will be projected into the cup 10 tending to force it upwardly toward its seat. The upper surface of the valve is tapered upwardly and it is to be noted that the outer portion of the beveled upper surface indicated at 12 is recessed or counter-sunk slightly below the central upper portion, to form a shoulder 13 which fits within the valve seat above. g

The valve seat let is a ring the outer surface of which is threaded to screw within a recess in the lower end of the coupling section 4. This ring has its lower inner edge beveled at 15 to contact with the surface 12 of the valve. The valve seat has a plurality of inwardly projecting lugs 16 thereon to receive a wrench of ordinary construction whereby the valve may be screwed into and from the recess in the coupling section.

The outer part of the valve is formed with a plurality of spacing wings 17 thereon which lit at their outer edges against the inner wall of the chamber 6, allowing the valve to slide freely in the chamber but holding it in spaced relation centrally of the chamber. I

In the use of this device the valve will be normally opened due to the flow of fluid pumped downwardly through the drill stem. The fluid passing through the upper section 4 of the valve housing will be projected against the upper tapered surface of the valve and be deflected away from the seat 12 below the shoulder 13 so that there will be little wear upon the seat through erosion by the flushing fluid.

When gas pressure is encountered tending to blow upwardly through the drill stem the fluid coming through the passage 9 below the cup of the valve will engage within the valve and throw it instantly closed before any gas may escape around the valve into the upper passage. This will prevent any'injury to the hose connections with the upper end of the drill stem or to the pumps and will also stop the blow-out of fluid before it has gained any momentum.

When the valve has thus been closed it is held in its seat by the gas pressure below and this pressure may be so high as to prevent a valve from opening. The drive stem is then disconnected from the upper end 5 of the coupling and a special attachment is employed for moving the valve. This attachment is shown in Fig. 1. The lower end of this attachment is intended to act as a cross to allow the liquid or other fluid to be directed laterally away from the well. The lower end is threaded at 18 to fit within the socket 5 of the valve member and two lateral openings 19 are provided connecting with nipples 20 which may be connected through pipe with any desired place of storage. The upper end of the cross is provided with a threaded passage 21 to receive a shaft 22 threaded between its ends to engage within the seat 21.

Above the threaded seat 21 there is a stuffing box including packing 23 and a gland 24 held in place by a threaded cap 25 screwing over the upper end of the attachment.

The shaft 22 extends downwardly through the attachment, its lower end being tapered In the operation of this device it will be employed in the manner already set forth. The valve will automatically close with the increase of pressure from below the same and will remain closed until provision is made through the use of the attachment 18; and the valve may then be opened and the fluid directed to a proper place for storage or waste. The structure forms a valuable means of preventing a blowout when the pressure is high, but allows the operator to control the flow of fluid from the well without difficulty.

Having thus described our invention, what we claim as new is:

1. A drill stem attachment comprising a housing adapted to be connected with the up per end of said drill stem, a valve adapted to close upwardly under fluid pressure from the well, a threaded socket at the upper end of said housing, a cross having lateral outlets therein formed to screw into said socket, and an elongated rod in said cross adapted to be screwed downwardly and unseat said valve to allow fluid to flow from said drill stem to said lateral outlets.

2. A drill stem attachment including a tubular housing threaded for connection with the upper end of the drill stem. a valve chamber therein, a valve freely slidable in said chamber, said valve being held normally open by gravity and adapted to seat upwardly through fluid pressure from the well, a cross shaped fitting on said housing and a rod movable downwardly through said fitting to engage and move said valve from its seat.

In testimony whereof we hereunto allix our signatures this 14th day of June. A. D. 1928.

ELLSl/VORTH GRAY. ROBERT A. MUELLER. 

